We got your good bed bug news and your bad bed bug news.

The good news? Even as news reports say that bed bugs have invaded City Hall, bed bug complaints are way down in NYC. The number of bed bug complaints taken by 311 and forwarded to Housing Preservation and Development, for example, sank from 7,760 for the Jan. 1-May 23 period in 2012 to 3,950 for the same period this year — a drop of almost 50%.

Reports taken by 311 involving the Department of Education (bed bugs are in schools, too) declined from 366 in 2012 during the same time to 205.

And while there was an uptick of violations issued by HPD in fiscal year 2015 to a total of 2,881 — which was 155 over the previous fiscal year, violations have fallen since fiscal year 2011, when 4,451 such orders were issued.

The bad news? Experts say that bed bugs are literally growing thicker skins (“integuments” in entomological parlance) that make them resistant to a common insecticide, and that if complaints are down, it’s because people aren’t complaining and not because the pests are disappearing from our private and public spaces.

“Residents don’t complain to the city about bed bugs any more, but the problem is still acute,” said Glenn Waldorf, a director at Bell Environmental Services, based in Fairfield, N.J. “When people have bed bugs, they want the problem solved: They call respected professionals,” who can respond immediately, rather than wait for city inspectors, Waldorf explained.

The eradication business is booming and particularly robust now that summer has begun, say exterminators. Summer is the season when bed bugs are friskiest and people are on the move, carting the critters with them to infect more places. People sharing homes, cars, bikes and other belongings — often to lessen costs and carbon footprints — is also helping bed bugs hitchhike more proficiently, said Rich Kane, owner of Bed Bug Pest Prep NYC.

Most people have no idea how bed bugs found their way into homes, theaters and offices, and investigations sometimes yield surprising findings.

A helpful do-gooder in a luxury West Village building who accepted packages for his celebrity neighbors turned out to be the source of his building’s bed bug infestation, recounted John Furman, owner of Boot A Pest, a Nassau County, Long Island, exterminator that works in NYC. “He had thousands of bed bugs on his toilet seat,” some of which were distributed via the packages, Furman said. He has also seen the parasites use electrical wires between apartments as hiking paths.

Avoiding bed bugs is important, especially now that they are getting harder to kill: “The exoskeletons are definitely tougher, making it harder for the products to penetrate,” he said. Furman and others had their suspicions borne out earlier this year when a paper in the Public Library of Science documenting a “highly pyrethroid-resistant field strain” of bed bugs in Australia that had thicker outer layers. Furman ups his game in the bug wars by concocting cocktails of as many as four different chemicals to eradicate the insects.

Locally, “a very high percentage of bedbugs have genetic mutations that make them resistant,” to common pesticides, wrote Louis Sorkin, a senior scientific assistant at the American Museum of Natural History in a paper about the insect’s genomic sequencing. The study collected bed bugs from 1,400 NYC sites (“including every subway station”) documenting differences and similarities of what one scientist called “one of New York City’s most iconic living fossils.”

Kane said that the over-the-counter sprays, which contain inadequate concentrations of deadly chemicals, are a culprit behind the “what doesn’t kill them makes them stronger” adaptation, spurring the hardiest bugs to “morph,” not unlike when bacteria mutates and becomes antibiotic resistant. “Foggers,” which tend to scatter the bugs, that return after the toxic mist abates, are another factor, he added.

Few of his clients report the problem to NYC.

Nor did S., a 24-year-old Harlem man who endured two bed bug infestations. Trashing mattresses and many belongings cost his family at least $2,000, he said.

S. did not want his name used because, he said, having an infestation is traumatic and stigmatizing. “You can see (the bites) on your body!” he added.

But “I never reported them to the city,” said S., as he was afraid the landlord might use the issue as an excuse to evict his family — even though it is legally a landlord’s responsibility to exterminate the pests.